The body includes various passageways including blood vessels, such as arteries, urinary, biliary, tracheobronchial, esophageal or renal tracts, and other body lumens. These passageways sometimes become occluded or weakened, or otherwise structural support may be desired. For example, they can be occluded by a tumor, restricted by plaque, or weakened by an aneurysm. When this occurs, the passageway can be reopened or reinforced, or even replaced, with a medical endoprosthesis. The endoprosthesis may be implanted in a passageway or lumen in the body. Many endoprostheses are tubular members, examples of which include stents, stent grafts, covered stents, aortic valves, etc.
Some endoprostheses are made from fully bioabsorbable materials which will gradually dissolve or be absorbed by the body over a period of time after implantation. Other endoprostheses are made from biostable materials, such as biostable metallic materials and/or polymeric materials which will remain in the body lumen indefinitely after implantation.
The endoprosthesis should exhibit sufficient strength to retain the endoprosthesis at the desired location within the anatomy. For instance, regarding stents configured to be placed proximate an aortic ostium, it may be desirable to configure the stent to have a proximal region positioned proximate the aortic ostium that is stronger than a distal region of the stent extending into the coronary artery away from the aortic ostium due, at least in part, to the larger forces involved and the larger diameter of the vessel on the ostium side. However, it may be desirable to maintain flexibility along other portions of the stent. In other applications, such as in the tortuous vasculature, it may be desirable to utilize a stent that provides sufficient initial stability to the vessel, but over time restores vasomotion in the stented vessel.
Accordingly, it may be beneficial to provide alternative endoprostheses as well as methods for manufacturing and using the alternative endoprostheses that provide sufficient structural support while maintaining a desired flexibility. Some embodiments are therefore directed to several alternative designs of endoprosthesis structures and assemblies, as well as methods of making and using the alternative endoprosthesis structures and assemblies.